1. Field of the Invention
This invention relates to an internal combustion engine that has a fuel injection valve for directly injecting fuel into a combustion space.
2. Description of the Related Art
In a spark-ignition internal combustion engine of recent years, a so-called direct-injection internal combustion engine for directly injecting fuel into a combustion space to create an air-fuel mixture with air contributing to the combustion has been put to practical use. The direct-injection internal combustion engine is also operable by so-called homogeneous combustion where the fuel and air are homogeneously mixed inside the combustion space to combust the fuel by injecting the fuel into the combustion space during an intake stroke. In the homogeneous combustion operation, it is important to diffuse the fuel and air homogeneously to mix the fuel and air as homogeneously as possible in order to attain good combustion.
Japanese Patent Application Publication No. 10-159619 (JP-A-10-159619) (paragraphs [0005] to [0008]) discloses a technology for obtaining a homogenous air-fuel mixture by injecting fuel into a combustion space at the first half and the second half of an intake stroke. Also, there has been put to practical use an internal combustion engine that has a direct injection valve for directly injecting fuel into a combustion space and a port injection valve for injecting fuel into an intake port, in which the port injection valve is used for homogeneously mixing the fuel and air at the time of homogeneous combustion.
However, such an internal combustion engine having a direct injection valve and port injection valve is complex in structure leading to an increase in production cost. Moreover, the technology disclosed in JP-A-10-159619 does not take, into consideration the flow of air flowing into the combustion space.